1. Field of Invention
The present invention relates to a light emitting chip with a heat dissipating structure, which is applicable as the light source for an LED. The light emitting chip is composed of epitaxy chip and electrodes, and uses insulating material with good heat dissipation material to form the substrate of the emission layer. The invention is a light emitting chip with heat dissipating structure built on the substrate.
2. Related Art
Light emitting diode (LED) was invented in the 1970s, and has since influenced the human life dramatically. In the following decades, people have been searching for more practical and efficient light sources. However, many technical bottlenecks cannot be overcome and no major breakthroughs have been made. Many problems still exist when LEDs are applied to daily life, such as light intensity, product life span, etc. In the recent years, due to many technical breakthroughs, LED applications are widely available. The LED has many advantages compared to the traditional light sources, such as: smaller volume, better emission efficiency, longer life span, faster operation and reaction speed, higher reliability, more robust, and can be integrated into small sized, coiling or arrayed elements. These LEDs have no thermal radiation and no toxic material pollution, as with elements such as mercury.
The current LED production technique has already become quite mature, so has improved the level of the light intensity. The current applications for LED include: car dashboard displays, backlit sources for liquid crystal display (LCD) panels, interior lighting, light sources for scanners and fax machines, etc. Future developmental goals focus on producing LEDs with low power consumption, while staying highly efficient and maintaining good light intensity. Also, the micro LED is another important goal. Miniature LEDs are used as the light sources in electronic devices, such as cellular phones, laptops or in the backlit panel of PDA screens. The surface bonding LED is suitable for this kind of demand.
When considering light emitting efficiency, the amount of power acceptable by the light emitting chip in the LED is an important factor. Applications of the high-power light emitting chip can increase the light intensity of a single LED, and thus increase the application range of the LED to areas such as illumination. Therefore, increasing the power of the light emitting chip is a huge challenge when increasing the light intensity of the LED. When increasing power, the first problem is to dissipate heat and lower the raised working temperature as electrical current flows through the light emitting chip. By observing the information disclosed from the known technology, it can be seen that most LEDs have heat dissipating structures added during packaging, which are exterior heat dissipating devices, such as liquid cooled LEDs and air-cooled LEDs. Such heat dissipation design uses exterior utilities, such as sealed masks filled with liquid or gas, to help disperse the working temperature generated by electricity flowing through the LED. Therefore, the working temperature will not get too high and the LED can sustain high-power consumption and not cause optical attenuation. However, even though the exterior design can achieve heat dissipation, it also increases the packaging procedures. Checking whether the exterior heat dissipating design is efficiently combined during packaging is an extra step during the quality control process.
Please refer to FIG. 1 for the illustration of the light emitting chip 10 with heat dissipating substrate, composed of epitaxy chip 11, electrodes 12, and heat dissipating substrate 13. This structure is from the previous invention of the light emitting chip with good heat dissipation. Special material is used for the heat dissipating substrate 13, and heat is dispersed using the characteristics of the substrate. When the epitaxy chip 11 on the light emitting chip 10 conducts the working temperature through electrodes 12 to the heat dissipating substrate 13, heat can be easily dispersed through the substrate 13. The inventor has disclosed that the main material for the substrate consists of ceramics, aluminum oxides or aluminum nitrides, since all these material have a good thermal conduction rate and are suitable for the substrate of the light emitting chip. The invention also aims to design a light emitting chip with a better dissipation rate that is ideal for a wider application range.